Renowned British chimpanzee expert Jane Goodall dies at 91

British anthropologist Jane Goodall holds a baby Cariblanco monkey in Santiago, on November 23, 2013. [Hector Tetamal, AFP]

British primatologist Jane Goodall, who transformed the study of chimpanzees and became one of the world's most prominent wildlife advocates, has died at the age of 91, her institute announced Wednesday.

Goodall "passed away due to natural causes" while in California on a speaking tour of the United States, the Jane Goodall Institute said in a statement on social media.

"Dr Goodall's discoveries as an ethologist revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world," the statement added.

Born on April 3, 1934, in London, Goodall's fascination with animals began in early childhood, when her father gave her a stuffed toy chimpanzee that she kept for life.

She was also captivated by the Tarzan books, about a boy raised by apes who falls in love with a woman named Jane.

In 1957 she traveled to Kenya at the invitation of a friend, where she began working for the renowned paleontologist Louis Leakey.

Her breakthrough came when Leakey dispatched her to study chimpanzees in Tanzania. She became the first of three women he chose to study great apes in the wild, alongside American Dian Fossey (gorillas) and Canadian Birute Galdikas (orangutans).

Goodall's groundbreaking observations included her discovery that chimpanzees use grass stalks and twigs as tools to fish termites from their mounds.

On the strength of these findings, Leakey encouraged her to pursue a doctorate at Cambridge University, where she became only the eighth person ever to earn a PhD without first obtaining an undergraduate degree.

Her activism was sparked in the 1980s after attending a US conference on chimpanzees, where she learned of the threats they faced: exploitation in medical research, hunting for bushmeat, and widespread habitat destruction.